1. Field of the Invention
The present invention relates generally to intravascular catheters, and more particularly to balloon dilation catheters suitable for angioplasty procedures.
2. Description of the Related Art
Balloon dilation catheters can be used in a variety of medical procedures and are most widely associated with percutaneous transluminal coronary angioplasty (PTCA). This procedure typically involves introducing a balloon dilation catheter into a patient's vascular system and advancing the catheter to a stenosis or other blockage site within a coronary artery. The balloon is then inflated by supplying fluid under pressure to the balloon. The inflation of the balloon stretches the artery, thereby dilating the stenosed region and restoring the diameter of the artery for increased blood flow.
One or multiple dilations may be necessary to effectively dilate the artery. In many instances, multiple dilations using multiple "over-the-wire" catheters having balloons with increasingly larger diameters may be required. An over-the-wire catheter is one where a separate guidewire lumen is provided so that the catheter can be guided to the stenosis site by running the catheter along the guidewire. In a typical procedure, a physician will first insert and advance a guidewire to the stenosis site. An initial over-the-wire balloon dilation catheter having a fairly small diameter balloon is then passed over the guidewire to the site and the balloon is inflated to partially dilate the vessel, then deflated and the catheter withdrawn. Progressively larger balloon catheters are then advanced to the stenosis along the guidewire, inflated, deflated, and then withdrawn in succession to sufficiently enlarge the opening.
In order to treat stenoses in small arteries, or to treat stenoses having small diameter openings, there have been continuing efforts to reduce the profile of balloon dilation catheters. One disadvantage of over-the-wire balloon dilation catheters is that the overall profile of these catheters is limited due to the provision of both a guidewire lumen and an inflation lumen for inflating the balloon catheter. So-called "fixed wire" catheters have been developed that provide for a lower profile. These catheters are generally fixed to a guidewire or guiding member for advancement to a site of stenosis advance and therefore a guidewire lumen for relative movement between the guidewire and catheter is not required, allowing for a reduced profile relative to an over-the-wire catheter. The lower profile allows these catheters to cross tighter lesions and to generally be advanced deeper into coronary vasculature. The disadvantage of such catheters is that the physician is unable to maintain position at the stenosis site when withdrawing the catheter and replacing it with one having a different balloon diameter. Instead, the path to the stenosis must be continually reestablished.
Therefore, a need exists for reduced profile dilation catheters that can be advanced over a guidewire positioned at a stenosis site. A further need exists for such catheters that are easily manufactured, durable and easy to use.